Electronic distributor module failure

[maleah 17]

Im burning through electronic modules quickly.  I currently have a Petronix flame thrower distributor with a series II module with less than 500 miles on it.  Im using a Accell coil. What would cause a module to stop working?  This is the 3rd module in a year.  What can I do to prevent these failures?  Any hep would be appreiciated!  Mike

[Rsmach1 71]

Have you checked the voltage going to the module? What is it? If you're using the stock resistor wire that could be the problem. Pertronix says it's "ok" to use but many have found including myself, removing the resistor wire and giving the module a full 12v solved the problem. Also be sure to check the engine ground.

[Flanders 46]

I 2nd Rsmach1's opinion.  A low voltage caused drivability issues (when warm) and ultimately pooched my module.

[maleah 17]

Would I wire the coil directly from the battery? Elsewhere? Could the module be getting to much voltage? Thanks for the replys.

[Mach1 Driver 560]

Would I wire the coil directly from the battery? Elsewhere? Could the module be getting to much voltage? Thanks for the replys.

If you go directly to the battery you will never be able to turn the car off.

The ignition switch has several internal switches; the one you are interested in is B to C. It is closed when the key is in the "start" or "on" (run) position. The resistor wire is connected between C and Bat on the ignition coil. You can bypass the resistor wire and leave it in the circuit. Look at your voltage regulator (below the starter solenoid). The plug on the regulator has various wires in it. The second terminal down is wire 904 which is green with a red stripe. It may have a second short wire coming out that has a bullet connector on it. You can connect to either one of these wires and go directly to the coil Bat terminal. This will bypass the resistor wire and do what Pertronix suggests.

This may not help your problem though. The module is blowing up because either it doesn't like the supply power or the load. Low supply power (because the resistor is still in the circuit) is unlikely to blow it up- it would just fail to operate. Since Pertronix doesn't say you have to bypass the resistor wire it is unlikely that this is the problem. The load (the coil) however is what the module is running and if it requires too much current to flow through it (more than the module can handle), the module will eventually fail. I would use a Pertronix coil or at least check what the manufacturer says the coil's primary resistance is. A stock coil is 1.5 ohms and higher output coils from Pertronix have primary resistances of 3.0, 1.5, 0.6 and 0.32 ohms. The less the primary resistance the higher the output voltage. 

Another possibility is that your coil has an internal short that causes too much current to flow through the module.

[Rsmach1 71]

What I did was to bypass the resistor wire by removing it and replacing it with a 14g wire. Yes Pertronix says it's OK to use the stock resistor wire, but after going through 2 igniters in 6 months, I was told (in another forum) to remove the resistor wire from the picture, and I've had no problems since.

[Mach1 Driver 560]

What I did was to bypass the resistor wire by removing it and replacing it with a 14g wire. Yes Pertronix says it's OK to use the stock resistor wire, but after going through 2 igniters in 6 months, I was told (in another forum) to remove the resistor wire from the picture, and I've had no problems since. 

Point taken Rsmach1. Maleah said he "burned through modules quickly" and is now on the third in a year; which I took to mean the modules failed, but you are correct, It could just be low voltage in the ignition circuit. The ignition switch or the related wiring could have high resistance. With the resistor wire in the stock circuit there should be around 6.8v on the coil BAT terminal with the engine running and the alternator charging around 14.4v. Measure the charging voltage across the battery terminals and the other from chassis to the coil. If the voltage at the coil is significantly less then the module can't operate. I don't know what that voltage threshold is- Pertronix would have to say.

Maleah you said you are using an Accell coil- would that be the 8140? That's what popped up in a Google search. It has a primary resistance of 1.4 ohms with an output of 42KV. The stock coil is 1.5 ohms so this doesn't change the current much but the lower the primary resistance the higher the current. Ford doesn't share it's design data with us so we don't know how much amperage B to C in the ignition switch can handle. If your car already has high resistance in the circuit, stressing it with a low resistance coil will only make the problem worse. Eventually something will fail.

Take the voltage readings and replace the resistor wire as Rsmach1 did, or bypass it like I suggested. With the resistor bypassed you should get around 14.4v at the coil with the engine running. That just about doubles the coil primary voltage. That's what the wire on the starter solenoid "I" terminal does. It bypasses the resistor wire and gives full power to the coil to make it start quicker. Good luck.

 

 

[maleah 17]

Sorry guys. Was on vacation and couldn't get the results posted until now. When I got back from vacation the car started up, which means the module I not fried like I originally thought. Reading the meter I get 14 volts at the battery running and 13.6 at the coil positive terminal. When I increase the throttle the volts go down to about 12.9. Should this happen? When I drive the car is when it cuts completely off but only in 1st gear, under load at about 2500rpms. Will not cut off out of gear in neutral. I can rev it all the way to 4500 rpm and will not cut off. So what are my options? What would cause a voltage drop at the coil? Is this even my problem? Thanks for your help.

[Mach1 Driver 560]

An electro-mechanical voltage regulator should regulate from 13.5 to 15.3v. The fact that yours goes down below range at increased throttle is a bit odd, but it still has plenty of voltage and the ignition should still operate.

It sounds like a loose or high resistance connection somewhere. Bad grounds can cause bizarre operation so I would disconnect and clean them. I've seen cables that look good and test OK with an ohmmeter but have broken strands under the insulation and won't carry a load. 69's have the negative battery cable going directly to the engine and a secondary from the passenger side head to the firewall near the heater motor (this is a pretty hefty wire- maybe an 8 to 10 gauge). I've read that 70's don't have this wire but have a secondary one going to the chassis from the negative battery cable. Perhaps someone with a 70 can verify this if need be.

I hope it doesn't come to this, but as a last resort; Midlife (one of our members) sells reconditioned harnesses but he recommends a new harness for the engine bay because it is exposed to the elements and temperature extremes and is nearing 50 years old. The vendor he recommends for new harnesses is Metal Alloy.

[maleah 17]

I should note I have a one wire alternator hooked up with no voltage regulator attached, just directly attached to the green wire with red stripe.

[maleah 17]

Sorry I have a 3G alternator

[Rsmach1 71]

You're voltage issue is unusual, first thing I would do is check/replace the belt, slippage at rpm's above idle could cause a voltage drop. Might want to pull the alternator and have it tested just to be sure(many places test for free). As stated put before check the grounds and connections, make sure the engine ground is attached to a CLEAN UNPAINTED spot on the block itself.

 

Question, each time you replaced the module were you having the exact same symptoms? Did it seem to totally solve the issues? I ask because lack of fuel can cause the same symptom you're describing, an engine under load requires more fuel then one being revved standing still. May want to check the fuel filter, as well as full pressure.

[Rsmach1 71]

One more idea, do you still have the stock coil around? Or have someone that would let you borrow one to try? Only ask cause I've had crap luck with accell coils, and trying a known working coil without having spend $ playing "the swap" game.

[maleah 17]

Funny you should mention the belt. I tightened it up as I thought the same thing. I just took readings again, tested the voltage coming out of the coil wire (to the distributor) and am getting 12 volts. Tested spark at the spark plug wire and getting nothing, which now leads me back to thinking its th module. Funny stuff, my car certainly challenges me at times. I did put a stock coil back on and same results as my accel coil, minus a few volts. The car started fine yesterday and now again won't start at all? And yes, each time I replaced the module car worked fine for a few months and then would just cut off while driving.

[Rsmach1 71]

That stinks, well if still under warranty have em replace it... again. See what their tech guys have to say. After a quick search seems the II might have some issues on other forums. Maybe try the original ignitor, that's what I ran in my car, and after loosing the resistor wire it gave me year's of trouble free service. Do a search on the III and see what ya find, if you find a lot of positives, tell Pertronix you want to upgrade and see if they'll help you out because of all the PROBLEMS, WORK, and DOWNTIME you've suffered. Be nice but firm, tell em you'd like let the forum's know they took care of you.

Let's see how important customer service is to them. Let us know how they treat you.

 

Good luck, Randy.